This application claims the benefit of a priority under 35 USC 119 to French Patent Application No. 01 13685 filed Oct. 23, 2001, the entire contents of which are hereby incorporated by reference.
This invention is directed to a method and device for X-ray emission and, more particularly, to a method and device for X-ray emission with gas trapping The device is useful in medical imaging of a body by radiography.
Conventionally, an X-ray emission device comprises an X-ray tube provided with an anode and a cathode subjected to a very high potential difference, up to as much as 150 kV. The X-ray tube is disposed within a protective enclosure. The protective enclosure is filled with an electrically insulating liquid intended to insulate the tube electrically and to cool it on operation, such as electrically insulating oil. The casing of the enclosure is provided with a window through which the X-rays emitted from the tube are delivered out from the emission device.
In operation, the X-rays propagated in the electrically insulating liquid generate, induce, cause, form or maintain in the liquid chemical reactions that produce gases, such as hydrogen, propane, methane, etc. These gases are in a dissolved form in the liquid. However, when the liquid is saturated, gas bubbles are created in the enclosure. These gas bubbles may markedly disrupt or strongly disturb the operation of the device. The presence of gas bubbles alters or impairs the electric insulation qualities of the liquid and can result in a cutoff of emission of the X-rays by appearance of an electric arc short-circuiting the cathode and the anode. The gas bubbles are, furthermore, capable of causing the destruction of some of the components of the device and, in particular, of the X-ray tube.
In an embodiment of the invention, an X-ray emission device comprises an X-ray tube and a protective enclosure filled with an electrically insulating liquid, in which the X-ray tube is placed. In an embodiment of the invention, the device further comprises means of elimination or removal or extraction of gas bubbles contained in the liquid filling the protective enclosure.
In an embodiment of the invention, the means for elimination or removal or extraction comprises at least one chamber that traps the gas bubbles in communication with the protective enclosure. An assembly comprising the device and the trapping chamber is movably mounted in a generally circular notion, the chamber trapping the gas bubbles in a region radially inside the chamber, in the course of its displacement.
In an embodiment of the invention, the trapping chamber can be, for example, generally disk-shaped and may be provided with a peripheral cavity equipped with means for purging or draining the chamber. In an embodiment of the invention, when in use, the means for purging the chamber may include a purge valve placed in high position of the trapping chamber, on closure or locking of the chamber.
In an embodiment of the invention, the means for purging of the chamber may include a filtration membrane placed in high position of the trapping chamber, on closure of the chamber, the liquid filling the protective enclosure circulating against one of the faces of the membrane.
In an embodiment of the invention, the chamber is equipped internally with a transverse plate, considering the direction of flow of the liquid entering the chamber, the plate being adjusted to direct the liquid to a peripheral cavity.
In another embodiment of the invention, the means for elimination or removal or extraction of the gas bubbles comprises a conduit element in communication with the protective enclosure and leading to a cavity trapping the gas bubbles, the cavity having a means for purging. An assembly comprising the device and the conduit element being movably mounted in a generally circular motion, the conduit element extending substantially radially inward, considering the path of the device, the conduit element directing the gas bubbles to the trapping cavity in the course of its movement. In an embodiment of the invention, the conduit element is preferably elbowed.
In an embodiment of the invention, the device, the means for eliminating or removal or extraction of the gas bubbles is mounted for cooperation with a means for cooling circuit for the electrically insulating liquid.
In an embodiment of the invention, an X-ray emission device comprises an X-ray tube and a protective enclosure filled with an electrically insulating liquid in which the X-ray tube is placed, the device intended to be moved in operation in a generally circular motion. In accordance with an embodiment of the device, the device comprises a generally disk-shaped gas bubble trapping chamber that is provided with a peripheral cavity equipped with a chamber purge valve.
In an embodiment of the invention an X-ray emission device comprises an X-ray tube and a protective chamber filled with a electrically insulating liquid in which the X-ray tube is placed, the device intended to be moved in operation in a generally circular motion. In an embodiment of the invention, the device comprises a conduit element in communication with the protective enclosure and leading to a gas bubble trapping cavity. An assembly comprising the device and the conduit element is movably mounted in a generally circular motion, the conduit element extending substantially radially inward, considering the path of the device, the conduit element directing the gas bubbles to the trapping cavity in the course of its movement.
In an embodiment of the invention, a method for eliminating or removing or extracting gas bubbles from a liquid of an X-ray emission device movable in operation in a generally circular motion and comprising an X-ray tube and a protective enclosure filled with an electrically insulating liquid in which the X-ray tube is placed. In an embodiment of the method, the liquid filling the enclosure may be continuously removed or drained, the liquid is passed into a gas bubble trapping chamber which is borne by the device which is provided with a peripheral cavity equipped with a chamber purge valve, the device and the chamber it bears are closed or locked, and the chamber is purged or drained.
In an embodiment of the invention, a method of elimination or removal or extraction of gas bubbles from a liquid of an X-ray emission device movable in operation in a generally circular motion comprises an X-ray tube and a protective enclosure filled with an electrically insulating liquid in which the X-ray tube is placed. In the course of operation of the device, the liquid filling the enclosure may be continuously removed or drained, the liquid is passed into a conduit element that extends substantially radially inward, considering the path of the device, which is driven in rotation on an axis of rotation different from the device, which is connected to the protective enclosure and which leads into a gas bubble trapping cavity, the device is closed or locked and the cavity is purged or drained.